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Asymmetric synthesis of hexapropionate synthons by sequential enantiotopic group selective enolization of meso diketones.

Organic letters (2006-06-02)
Dale E Ward, H Martin Gillis, Olukayode T Akinnusi, M Abdul Rasheed, K Saravanan, Pradip K Sasmal
ABSTRACT

Meso 1,9-diketones (six to seven stereocenters) are readily obtained by stepwise or simultaneous two-directional aldol reactions of tetrahydro-4H-thiopyran-4-one with a thiopyran-derived aldehyde or dialdehyde. Enantioselective enolizations of these diketones with the lithium amide from (R,R)-bis(1-phenylethyl)amine occur with simultaneous kinetic resolution to give the mono-TMS enol ethers in >90% yields (BORSM) and >95% ee. The products are applicable to polypropionate synthesis. [reaction: see text]

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Tetrahydro-4H-thiopyran-4-one, 99%